The study, which was conducted by researchers at Johns Hopkins Bloomberg School of Public Health and published in the journal Medical Care, could shed some light on why life expectancies among older Americans are decelerating.
In the analysis, researchers found that having multiple chronic medical conditions after retirement age significantly decreases life expectancy.
To conduct their analysis, the researchers, led by Eva H. DuGoff, used a nationally representative sample of Medicare beneficiaries who were enrolled as of January 1st, 2008. This involved the records of nearly 1.4 million people over the age of 67 with 21 defined chronic conditions.
The team explains that in the US, life expectancy is rising more slowly than in other parts of the world. The obesity epidemic is largely to blame, as well as its associated health conditions, the researchers note.
Though a 75-year-old woman in the US with no chronic conditions will live an additional 17.3 years on average, the team found that a 75-year-old woman with five chronic conditions will only live an average of 12 years and a woman with more than 10 conditions will only live 5 more years.
Additionally, the analysis revealed that women still live longer than men, and white people live longer than black people.
Commenting on their findings, DuGoff says:
"Living with multiple chronic diseases such as diabetes, kidney disease and heart failure is now the norm and not the exception in the US. The medical advances that have allowed sick people to live longer may not be able to keep up with the growing burden of chronic disease."
She adds that "preventing the development of additional chronic conditions in the elderly could be the only way to continue to improve life expectancy."
'System not set up for people with so many different illnesses'
But the number of diseases a person has is not the only determining factor in life expectancy. The team found that what type of disease a person has plays a role. For example, a 67-year-old individual with heart disease will live an additional 21.2 years, whereas someone with Alzheimer's disease is only expected to live an additional 12 years.
Though life expectancy decreases by 1.8 years with each additional condition, the researchers say the impact increases with more diseases.
"We tend to think about diseases in isolation," says senior author Prof. Gerard F. Anderson, from Johns Hopkins. "You have diabetes or you have heart failure. But many people have both, and then some."
Prof. Anderson adds:
"The balancing act needed for care for all of those conditions is complicated, more organ systems become involved as do more physicians prescribing more medications. Our system is not set up to care for people with so many different illnesses. Each one adds up and makes the burden of disease greater than the sum of its parts."
The researchers conclude their study by noting that Social Security and Medicare planners may find their results helpful in making population and cost predictions for the future, adding that they "should account for the growing number of beneficiaries with multiple chronic conditions when determining projections and trust fund solvency."
According to the team, 60% of Americans who are 67 and older have three or more chronic diseases.
Earlier this year, Medical News Today reported on a study that suggested loss of the Y chromosome in blood cells prompts men to have a shorter life span than women.